Tractor Repair: 885 case ih 2 speed not shifting when tractor heats up., electric solenoid, solenoid valve

Question
My 885 case ih does not want to shift  from hi to low when the tractor heats up. If it is stuck in hi the dump valve does not dump. If I leave it in low it will dump. When the tractor is cold or I don't use it to hard it all works fine.I've cleaned all electrical connection fuse,fuse panel,switches ect.I've replaced pump,flow divider.Also if left in hi the brake system will go empty.I've worked on tractors for years but this one has got me stumped.I would appreciate any information you have.thank you

Answer
 There is an internal electric solenoid valve that actually does the shifting by directing oil to the HI clutch pack when the HI/LO switch is in HI.  When it is in HI, the clutch pedal switch will cut the power to the solenoid to put it back in LO when the pedal is pushed.  So if it is already in LO, the clutch pedal switch doesn't do anything and it doesn't need to dump. There really is no dump valve on these like on the larger series tractor TA.  The clutch pedal switch simply shuts off the power to the solenoid just like if you move the HI/LO switch to LO.  Because the solenoid has to be energised for it to be in HI, an electrical problem will usually cause it to stay in LO and not shift to HI.  Since you have the opposite problem with it staying in HI and not shifting to LO, and because it happens after it warms up, the solenoid valve is probably sticking when it gets hot.  If it works when it is cold, then the HI/LO switch and clutch pedal switch should be OK.  I don't see how the brake problem could be related to this problem though.  There is an orifice in one of the oil cooler lines that supplies a small amount of oil to the brake reservoir to keep it full.  A plugged orifice will not keep it full, but shouldn't matter if it is in HI or LO.